Braiding Yarn Made of Expanded Graphite

ABSTRACT

The present invention relates to a braiding yarn made of expanded graphite for a gland packing which is to be used in a shaft seal part of a fluid apparatus or the like. In the braiding yarn made of expanded graphite of the invention, an expanded graphite tape ( 2 ) of a predetermined width is folded into a valley fold in the longitudinal direction, both end portions ( 2   a   , 2   b ) in the width direction of the expanded graphite tape ( 2 ) are bent so as to be directed toward the inner side of the width direction of the expanded graphite tape ( 2 ), and the outer periphery of the tape is covered by a reinforcing member ( 3 ) configured by a braided body of stainless steel wires. The expanded graphite tape ( 2 ) may be twisted. Reinforcing fibers may be embedded in the expanded graphite tape ( 2 ). Part of expanded graphite particles on the side of the surface of the expanded graphite tape ( 2 ) may be removed away. According to the expanded graphite tape of the invention, flaking of expanded graphite particles during a braiding process is reduced or prevented from occurring, and the pressure resistance of a gland packing can be enhanced.

DESCRIPTION

[0001] 1 Technical Field

[0002] The present invention relates to a braiding yarn made of expandedgraphite for a gland packing which is to be used in a shaft seal part ofa fluid apparatus or the like, and more particularly to a braiding yarnmade of expanded graphite which can enhance the pressure resistance of agland packing.

[0003] 2. Background Art

[0004] Conventionally, as a braiding yarn for a gland packing which isto be used in a shaft seal part of a fluid apparatus or the like, knownis, for example, a braiding yarn 1 shown in FIG. 8. In the braiding yarn1, an expanded graphite tape 2 of a predetermined width is folded into avalley fold in the longitudinal direction, and the outer periphery ofthe tape is covered by a reinforcing member 3 configured by a braidedbody of a metal wire.

[0005] A gland packing is produced by bundling and braiding a pluralityof the braiding yarns 1. However, the expanded graphite tape 2 is low intensile strength and brittle, and edges of both end portions 2 a, 2 b inthe width direction have low flaking resistance among expanded graphiteparticles. In edges of both end portions 2 a, 2 b in the widthdirection, namely, expanded graphite particles easily flake off. In thecase where, during a braiding process, large tensile and sharing forcesact on the edges of both end portions 2 a, 2 b in the width direction,therefore, cracks are formed with starting from the edges of both theend portions 2 a, 2 b in the width direction, and expanded graphiteparticles in and in the vicinity of the edges of both the end portions 2a, 2 b in the width direction flake off. When a plurality of braidingyarns are to be braided, consequently, a large tensile force cannot beapplied to the braiding yarns, so that the tensile force of the braidingyarns is limited to a low level. As a result, the pressure resistance ofa gland packing cannot be enhanced.

DISCLOSURE OF INVENTION

[0006] It is an object of the invention to provide a braiding yarn madeof expanded graphite in which flaking of expanded graphite particlesduring a braiding process is reduced or prevented from occurring, andthe pressure resistance of a gland packing can be enhanced.

[0007] In order to attain the object, the braiding yarn made of expandedgraphite according to the invention is characterized in that, in abraiding yarn made of expanded graphite which is to be used in a glandpacking, an outer periphery of a bent expanded graphite tape is coveredby a reinforcing member configured by a knitted body or a braided body,and at least one end portion in a width direction of the expandedgraphite tape is bent to be directed toward an inner side in the widthdirection of the braiding yarn.

[0008] Furthermore, the braiding yarn made of expanded graphiteaccording to the invention is characterized in that, in a braiding yarnmade of expanded graphite which is to be used in a gland packing, anouter periphery of a twisted expanded graphite tape is covered by areinforcing member configured by a knitted body or a braided body, andat least one end portion in a width direction of the expanded graphitetape is bent to be directed toward an inner side in the width directionof the braiding yarn.

[0009] According to the inventions, it is a matter of course thatcutting of the bent or twisted expanded graphite tape which may becaused by a tensile or twisting force during a braiding process iseffectively prevented from occurring by the reinforcing member coveringthe outer periphery of the tape. Since at least one end portion in thewidth direction of the expanded graphite tape is bent to be directedtoward the inner side in the width direction, moreover, large tensileand sharing forces do not directly act on the edges of the one endportion during a braiding process, and hence occurrence of cracks fromthe edges of the one end portion and flaking of expanded graphiteparticles due to the occurrence of cracks can be reduced. As a result,braiding at a larger tensile force is enabled, and the pressureresistance of a gland packing can be enhanced.

[0010] Furthermore, the braiding yarn made of expanded graphiteaccording to the invention is characterized in that reinforcing fibersare embedded in the expanded graphite tape. According to the invention,since reinforcing fibers are embedded in the expanded graphite tape, thetensile and twisting forces of the expanded graphite tape can beimproved.

[0011] Furthermore, the braiding yarn made of expanded graphiteaccording to the invention is characterized in that part of expandedgraphite particles on a side of a surface of the expanded graphite tapeare removed away. According to the invention, part of expanded graphiteparticles which are on the side of the surface of the expanded graphitetape, and which are highly oriented at a high density where crackseasily occur are removed away by a blasting process. During a braidingprocess, even when a large tensile force acts on the expanded graphitetape, therefore, occurrence of cracks and flaking of expanded graphiteparticles due to the occurrence of cracks can be reduced more surely.

BRIEF DESCRIPTION OF DRAWINGS

[0012]FIG. 1 is a perspective view showing an embodiment of theinvention.

[0013]FIG. 2 is a perspective view showing another embodiment of theinvention.

[0014]FIG. 3A is an enlarged section view showing a further embodimentof the invention.

[0015]FIG. 3B is an enlarged section view showing a still furtherembodiment of the invention.

[0016]FIG. 4 is a perspective view showing a still further embodiment ofthe invention.

[0017]FIG. 5 is a perspective view showing a still further embodiment ofthe invention.

[0018]FIG. 6A is a perspective view showing a still further embodimentof the invention.

[0019]FIG. 6B is a perspective view showing a still further embodimentof the invention.

[0020]FIG. 6C is a perspective view showing a still further embodimentof the invention.

[0021]FIG. 6D is a perspective view showing a still further embodimentof the invention.

[0022]FIG. 7A is a perspective view showing a still further embodimentof the invention.

[0023]FIG. 7B is a perspective view showing a still further embodimentof the invention.

[0024]FIG. 7C is a perspective view showing a still further embodimentof the invention.

[0025]FIG. 7D is a perspective view showing a still further embodimentof the invention.

[0026]FIG. 8 is a perspective view showing an example of a conventionalbraiding yarn made of expanded graphite.

BEST MODE FOR CARRYING OUT THE INVENTION

[0027] Hereinafter, preferred embodiments of the invention will bedescribed with reference to the drawings.

[0028]FIG. 1 is a perspective view showing an embodiment of the braidingyarn made of expanded graphite of the invention. Referring to FIG. 1, inthe braiding yarn 1 made of expanded graphite, an expanded graphite tape2 of a predetermined width is folded into a valley fold in thelongitudinal direction, end portions 2 a, 2 b in the width direction ofthe expanded graphite tape 2 are bent so as to be directed toward theinner side of the width direction of the expanded graphite tape 2, andthe outer periphery of the tape is covered by a reinforcing member 3configured by a braided body of stainless steel wires.

[0029]FIG. 2 is a perspective view showing another embodiment of thebraiding yarn made of expanded graphite of the invention. Referring toFIG. 1, in the braiding yarn 1 made of expanded graphite, an expandedgraphite tape 2 of a predetermined width is folded into a valley fold inthe longitudinal direction, only one end portion 2 a in the widthdirection of the expanded graphite tape 2 is bent so as to be directedtoward the inner side of the width direction of the expanded graphitetape 2, and the outer periphery of the tape is covered by a reinforcingmember 3 configured by a braided body of stainless steel wires.

[0030] The bending in the longitudinal direction of the expandedgraphite tape 2, and that of at least the one end portion 2 a toward theinner side in the width direction of the expanded graphite tape 2 arerequired to be realized at least during the braiding process. Before thebraiding process, therefore, the expanded graphite tape 2 may bepreviously bent, for example, into a V-like shape, and the one endportion 2 a may be slightly bent toward the inner side of the widthdirection of the expanded graphite tape 2. During the braiding process,the expanded graphite tape 2 and the one end portion 2 a may becompletely bent. The bent shape of the one end portion 2 a may be acurled shape, a spiral shape, a U-like shape, or another shape.

[0031] As the manner of covering the outer periphery of the expandedgraphite tape 2 by the reinforcing member 3 configured by the braidedbody of stainless steel wires, in place of the illustrated example, astructure may be employed in which, as shown in FIG. 3A and FIG. 3B,part of the reinforcing member 3 is interposed between both the endportions 2 a, 2 b in the width direction of the expanded graphite tape2.

[0032] The invention is not restricted to the case of the singleexpanded graphite tape 2. Alternatively, a plurality of expandedgraphite tapes 2 may be stacked together and then bent so that at leastone end portion 2 a in the width direction of each of the expandedgraphite tapes 2 is directed toward the inner side in the widthdirection of the expanded graphite tape 2.

[0033]FIG. 4 is a perspective view showing a still further embodiment ofthe braiding yarn made of expanded graphite of the invention. Referringto FIG. 4, in the braiding yarn 1 made of expanded graphite, both endportions 2 a, 2 b in the width direction of an expanded graphite tape 2of a predetermined width are bent so as to be directed toward the innerside of the width direction of the expanded graphite tape 2, the tape istwisted, and the outer periphery of the tape is covered by a reinforcingmember 3 configured by a braided body of stainless steel wires.

[0034]FIG. 5 is a perspective view showing a still further embodiment ofthe braiding yarn made of expanded graphite of the invention. Referringto FIG. 5, in the braiding yarn 1 made of expanded graphite, only oneend portion 2 a in the width direction of an expanded graphite tape 2 ofa predetermined width is bent so as to be directed toward the inner sideof the width direction of the expanded graphite tape 2, the tape istwisted, and the outer periphery of the tape is covered by a reinforcingmember 3 configured by a braided body of stainless steel wires.

[0035] The bending of at least one end portion 2 a toward the inner sidein the width direction of the expanded graphite tape 2 is required to berealized at least during the braiding process. Before or during thetwisting process, therefore, the one end portion 2 a may be previouslyslightly bent toward the inner side of the width direction of theexpanded graphite tape 2, and, during the braiding process, the one endportion 2 a may be completely bent. The bent shape of the one endportion 2 a may be a curled shape, a spiral shape, a U-like shape, oranother shape.

[0036] The invention is not restricted to the case of the singleexpanded graphite tape 2. Alternatively, a plurality of expandedgraphite tapes 2 may be stacked together and then twisted so that atleast one end portion 2 a in the width direction of each of the expandedgraphite tapes 2 is directed toward the inner side in the widthdirection of the expanded graphite tape 2.

[0037] As the material of the reinforcing member 3, in addition tostainless wires used in the embodiments described above, metal wiressuch as inconel, and monel, organic fibers such as cotton, rayon,phenol, aramid, PBO, PBI, PTFE, PPS, and PEEK, and inorganic fibers suchas carbon fiber, and ceramic fiber are useful. The reinforcing member 3may be braided by means of knitting.

[0038]FIGS. 6A to 6D are perspective views showing a still furtherembodiment of the braiding yarn made of expanded graphite of theinvention. The figures are different from the embodiments which havebeen described with reference to FIGS. 1 to 5, in that a plurality ofreinforcing fibers 4 are embedded in the longitudinal direction in theexpanded graphite tape 2 with forming gaps in the width direction.

[0039] As the reinforcing fibers 4, used is one selected from organicfibers such as cotton, rayon, phenol, aramid, PBO, PBI, PTFE, PPS, andPEEK; one selected from inorganic fibers such as glass fiber, carbonfiber, and ceramic fiber; or one selected from metal wires such asstainless steel, inconel, and monel Of course, the organic fibers, theinorganic fibers, and the metal wires may be adequately selected to becombinedly used.

[0040]FIGS. 7A to 7D are perspective views showing a still furtherembodiment of the braiding yarn made of expanded graphite of theinvention. The figures are different from the embodiments which havebeen described with reference to FIGS. 1 to 5, in that part of expandedgraphite particles which are on the side of the surface of the expandedgraphite tape 2, and which are highly oriented at a high density areremoved away by a blasting process.

[0041] The expanded graphite particles which are on the side of thesurface of the expanded graphite tape 2, and which are highly orientedat a high density are removed away by a microblasting process usingparticles which are smaller in diameter than the expanded graphiteparticles. Specifically, a blasting process is performed with using fineparticles (for example, a particle diameter of 15 μm) of SiC or the likeat an air pressure of 2 kg/cm² from a position which is separated by 150mm from the outer face of the expanded graphite tape 2. When amicroblasting process is performed in this way, expanded graphiteparticles in which cracks are easily caused and grown are removed awayfrom the surface 5 of the expanded graphite tape 2, and the flakingresistance of the expanded graphite particles which has been in a rangeof 30 to 40 g before the blasting process can be increased to a range of140 to 150 g.

[0042]FIGS. 7A to 7D show examples in which a blasting process isapplied to the embodiments which have been described with reference toFIGS. 1 to 5. It is a matter of course that a blasting process may beapplied to the embodiments of FIGS. 6A to 6D.

INDUSTRIAL APPLICABILITY

[0043] According to the invention, flaking of expanded graphiteparticles from one end portion of an expanded graphite tape during abraiding process can be reduced or prevented from occurring.

[0044] According to the invention, the tensile and twisting strengths ofan expanded graphite tape are improved, and the braiding yarn can besubjected to braiding at a larger tensile force.

[0045] According to the invention, flaking of expanded graphiteparticles can be more surely reduced or prevented from occurring.

[0046] In a process of braiding a plurality of braiding yarns,therefore, a defect that a large tensile force cannot be applied to thebraiding yarns and the tensile force of the braiding yarns is limited toa low level is eliminated, and braiding yarns can be braided at a largertensile force, so that the pressure resistance of a gland packing can beenhanced.

1. A braiding yarn made of expanded graphite which is to be used in a gland packing, wherein an outer periphery of a bent expanded graphite tape is covered by a reinforcing member configured by a knitted body or a braided body, and at least one end portion in a width direction of said expanded graphite tape is bent to be directed toward an inner side in the width direction of said braiding yarn.
 2. A braiding yarn made of expanded graphite which is to be used in a gland packing, wherein an outer periphery of a twisted expanded graphite tape is covered by a reinforcing member configured by a knitted body or a braided body, and at least one end portion in a width direction of said expanded graphite tape is bent to be directed toward an inner side in the width direction of said braiding yarn.
 3. A braiding yarn made of expanded graphite according to claim 1, wherein reinforcing fibers are embedded in said expanded graphite tape.
 4. A braiding yarn made of expanded graphite according to claim 2, wherein reinforcing fibers are embedded in said expanded graphite tape.
 5. A braiding yarn made of expanded graphite according to claim 1, wherein part of expanded graphite particles on a side of a surface of said expanded graphite tape are removed away.
 6. A braiding yarn made of expanded graphite according to claim 2, wherein part of expanded graphite particles on a side of a surface of said expanded graphite tape are removed away.
 7. A braiding yarn made of expanded graphite according to claim 3, wherein part of expanded graphite particles on a side of a surface of said expanded graphite tape are removed away. 